Direct and inverse variation y = k x y = kx k is like m meaning it is the slope Or the constant of variation This graph would be linear This graph would be exponential This graph has to go through the origin and makes a straight line This graph may or may not go through the origin and will not make a straight line

Y = -2X Y - intercept 0,0 X - intercept 0,0 X y 1 -2 2 -4 3 -6

Domain Range Y = 2/x or Y = (2)x X y -3 ⅛ -2 ¼ -1 ½ 1 2 4 3 8 Y X 1 2 4 3 8 X Domain Range All real numbers All positive real numbers

write a direct variation problem when y = 20 and x = 10 y = kx 20 = k·10 k = 2 y = 2x

write an inverse variation problem when y = 20 and x = 10 y = k x 20 = k 10 k = 200 y = 200 x

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